Highly active antiretroviral therapy (HAART) has had a great impact upon reducing AIDS related morbidity and mortality. However, due to the high degree of HIV-1 variation, novel strains resistant to the present HAART cocktail of drugs have arisen. Coupled with the considerable toxicity associated with HAART, there is significant need for the discovery of new antiviral compounds. To date, retroviral vector/packaging cell systems have been used primarily in gene therapy protocols. It is hypothesized here that an HIV-1 based vector/packaging cell system can be utilized in high throughput screening (HTS) for drug discovery. The reasons for this are: i) HIV-1 vector systems reproduce all aspects of virus replication in tissue culture, ii) marker genes providing simple readouts amenable to HTS can be incorporated into these systems, iii) these assays take less time than those involving replication-competent HIV-1 and are less labor intensive, and iv) a number of important safety features have been built into these systems. An advantage to this approach is that it would allow screening of a large number of targets, both known and unknown, as well as including aspects of replication involving virus-host cell interactions, which might be the most productive target areas. Preliminary studies with five known anti-HIV-1 drugs indicate that the system provides the necessary sensitivity for drug screening. Moreover, a HIV-1 derived vector expressing a marker whose activity can be detected using a multiplate reading luminometer has been developed. It has also been adapted to a 96-well format appropriate for HTS. Here we propose using HIV-1 derived vector systems for HTS to discover novel anti-HIV compounds.